Particulate and airborne molecular contaminants (AMC) pose considerable problems in semiconductor manufacturing facilities. These contaminants can cause reticle defects such as hazing. In general, reticle pods are used to protect reticles from these contaminants during storage and transport. Nonetheless, accumulation of these contaminants is common in reticle pods, which can degrade overall reticle quality. With such accumulation, there exists the opportunity for contaminants to enter the reticle pod when removing a reticle therefrom to use with a semiconductor tool. A typical approach for minimizing contaminants within a reticle pod involves periodic cleanings. One shortcoming with periodic cleanings is the potential for decreased manufacturing efficiencies.
Purging of wafers and reticles with nitrogen is known. Purging with nitrogen can eliminate contaminants in the reticle containment but presents problems in that nitrogen needs to be contained and controlled. Although nitrogen is not considered toxic, a nitrogen enriched environment with reduced oxygen, asphyxiation can result. Thus, leakages of nitrogen into space with personnel is not acceptable. Nitrogen enrichment can be detected only with sophisticated sensing equipment. Pure clean nitrogen is not inexpensive. Hazing can still occur with traditional nitrogen purging.
Thus, there remains a significant need for economically and safely protecting reticles during storage and transportation from contaminants and from hazing.